This invention relates generally to the field of partition wall construction, and more specifically to partition systems employing head tracks for interconnection of a suspended ceiling grid and partition walls.
It is general practice in the preparation of commercial office space and similar areas to present the tenant with a bare floor slab and perimeter walls, typically covered by a ceiling grid which covers the entire floor space. This floor space area is then partitioned off in a manner as pleases the tenant to form the spaces as required for the operation of his business. Typically the ceiling grid pattern includes a series of main T-bars and cross T-bars suspended from the main structural ceiling by hangar wires or other hangers. The T-bars are arranged to form an overhead grid work on which rectangular ceiling tiles and other fixtures are supported. The edges of the ceiling tiles rest on the flanges of the T-bars and are easily removable to provide convenient access to the area above the suspended ceiling.
The ceiling grid is supported on the perimeter walls using a component commonly referred to as "ceiling mold" or "ceiling angle" or "L-bar". This is an L-shaped angle having a vertical leg which lies along the exterior wall and a horizontal leg or lip which projects out from the wall into the room and supports the grid as well as forming a cosmetic border for the wall. Typically this "ceiling mold" is normally partially up the height of the exterior walls.
The reasons for installing partition walls below an existing ceiling grid are many. In large expanses it is more cost-effective to install an entire grid pattern due to both labor and material costs. When leasing areas, if a tenant leaves, remodeling is more cost-effective because of minimal ceiling patches, and because demolition and construction is easier for both enlarging or decreasing the side of the desired area. Of major concern, however, is the development of an attractive yet cost-effective material which would insure both an attractive finished appearance to match the perimeter walls as well as provide a structurally sound surface for anchoring the wall members and a finishing edge for the joint between the existing ceiling grid work and the wall partition.
When the interior partitions are erected, the common practice is to first attach a head track with an inverted "U" cross section to the ceiling, then mount vertical wall studs between the head track and a floor track, then attach drywall panels to both sides of the studs, and finally attach a separate trim piece on each side of the wall. The trim piece is typically an L-bead, such as shown in FIG. 1 of U.S. Pat. No. 4,074,478, or a series of outwardly flanged "L" shaped trim pieces attached to the face of the drywall (shown in U.S. Pat. No. 4,598,516), or a "T" shaped piece positioned behind the drywall (shown in U.S. Pat. No. 4,587,781). Another approach is to use a J-mold, shaped like an inverted "J" hooked over the top of the drywall.
In the case of the L-bead or J-mold, the main area of concern is the appearance of the joint between the top of the partition and the ceiling. In an L-bead or J-mold system, the drywall is typically applied so that its top edge is near the top of the head track. The L-bead or J-mold is attached in such a way that it is hooked over the upper edge of the partition, occupying the gap between the grid and the wall panel. In such a position, the bead is butted up against the underside of the ceiling tile. After placement of the mold, the finisher applies a series of coats of finishing compound to conceal the bead and give a suitable concealed appearance on the drywall for the application of paint or other wall treatment. The problem with this application is two-fold.
First, in the placement of the J-mold or L-bead, many times an uneven ragged edge is left at the top which the finisher must follow. This results in a rather unsightly appearance which detracts from the overall cosmetic effect of the partition. Second, it is extremely difficult to control the drywall compound perfectly even by the most skilled of craftsmen. Therefore, where ceiling tile is in place, unless the finisher exercises excessive and painstaking care, portions of compound will slip up onto the ceiling tile and stain the tile, requiring its replacement. This, in the course of finishing large areas, results not only in lost labor time, but also costly replacements of the ceiling materials.
This problem of tile staining is addressed by modifying the add-on trim pieces to include an overhanging flange as shown in U.S. Pat. No. 4,587,781, U.S. Pat. No. 4,598,516 and U.S. Pat. No. 4,074,478. These approaches, however, have another problem--increased construction costs. The addition of separate trim pieces entails many additional and costly labor hours due to the installation of these trim pieces, resulting in twice to three times the amount of time necessary to achieve the desired results. This increase in labor is largely due to the need to screw three elongated pieces into the ceiling grid: the head track; and two trim pieces. Each is attached as a separate operation, thus involving significant duplication of effort and consequent time expenditure. Other approaches, such as shown in U.S. Pat. No. 4,361,994, simplify construction and economize on the cost, but do not offer a finished trim appearance which matches the existing ceiling grid.
Costs in the prior art are high using separate trim pieces which must be fabricated, inventoried, stored, ordered, shipped and installed. Furthermore, excessive joint compound must be used in the prior approaches due to the need to cover trim pieces mounted on the outside of the drywall such as shown in U.S. Pat. No. 4,598,516. While these trim pieces may provide a suitable joint for finishing and a cosmetic trim effect, they detract from the overall cost and time effectiveness of the project being worked on by adding a substantial amount of labor time for their installation. Also, as these are not an integral part of the partition, the fastening or securing methods used may fail.